This application, Ser. No. 09/219,540 is a continuation in part of application Ser. No. 08/674,183, now abandoned, and is a divisional application of Ser. No. 08/437,430, dated May 5, 1995 now a granted U.S. Pat. No. 5,626,020.
1. Field of the Invention
This present invention relates to heat exchange media and more particularly to chemical compounds demonstrating reversible changes in physical state experienced during photostimulation with an associated absorption or release of heat. This invention further relates to the use of these compounds as a heat transfer or exchange medium.
2. Related Art
We have been unable to locate prior art pertaining to the use of photochromic compounds as a heat exchange medium. There is, however, a substantial body of prior art regarding the fabrication and use of photochromic compounds in applications such as optical data storage (Eich), optical switches (Kog u re), polarizing eyeglasses (Hares, ophthalmic lenses (Mann, Korn) and optical displays.
All of this prior art utilizes the physical property of photochromism, i.e. photoactivated color changes providing the effect in the desired system; polarized glasses, optical switches and lenses.
Jennings et al, U.S. Pat. No. 5,633,109, teaches the use of photochromic compounds as light sensitive indicators, which he encloses in liposome vesicles for mixture in ink compositions. Once the photochromic compounds are enclosed in the vesicles the ink can be used to print a document which is not visible under normal light. When the document printed using Jennings' ink composition is exposed to U-V light, the photochromic compounds become colored and thus the document becomes partially visible. Jennings does not teach the capture of these configuration changes in a solvent for use as a heat exchange medium.
Sangster et al, U.S. Pat. No. 5,626,020 teaches the use of a photochromic compound in combination with a polymer acting as a heat exchange medium, which will absorb and release heat based on photostimulation and heat gradients. Sangster et al, does not teach the composition of the heat exchange medium.
Luchina, AN 116224482, teaches the use of photochromic compounds in a solvent for use of its color and colorless properties. Luchina also teaches that a photochromic compound, when dissolved in solvents, can be driven to change color by thermal energy. Luchina, however does not teach that the change in color can also bring a change in spatial configuration of the molecule and the associated capture or release of heat.
Japanese patent 3-91,578, teaches the attachment of a spirooxazine compound by covalent linkage to alkyl or akyleneoxide side chains which can be polymerized to a concentration of side chain compounds of preferably more than 30 mol % for use in coatings. The spirooxazine mol % is not specified, however, since the major wt % of the combination should be the acrylic polymer or urethane polymer (at least 50 mol %) then the highest concentration of the spirooxazine compound could be in Japan patent 3-91,578 would be 20 mol %. At this concentration, the photochromic compounds would not experience a change in spatial configuration. Therefore the present invention is not taught by Japanese patent 3-91,578.
Japanese patent 3-81,378 teaches the use of a photochromic compound attached to a polymer and in an organic solvent for use as a colored ink. However the highest concentration of the photochromic compound in this invention is 10 mol %. At this concentration, none of the effects of spatial change in configuration or the capture or release of heat could be experienced, as in the present invention.
Japanese patent 2-164,809 teaches the use of a photochromic compound attached to a film forming polymer in a solvent for use as a colored fingernail polish. Since the combination experiences only normal change in coloration, that is, it becomes colored when exposed to LI-V irradiation, where in the present invention, our combination becomes colorless when exposed to U-V irradiation. This indicates that Japanese patent 2-164,809 could not experience a change in spatial configuration or the capture or release of he and does not teach the present invention.